The invention relates to a method of keeping a part such as a motor vehicle body wet between preparation stations during preparation for painting.
A method of preparing motor vehicle bodies for painting in a dippling arrangement is known, comprising a plurality of dipping tanks with different preparatory baths. Certain preparatory baths have temperatures considerably higher than ambient temperature. To transport the bodies between the dipping tanks, the bodies are placed in an enclosure which is open at the side facing the tanks and can travel above them.
The body, emerging from a bath at high temperature, is sprayed with water while in this enclosure, with spraying beginning as the body is withdrawn from the bath. The purpose of spraying is to keep the body wet, so that the heat absorbed by the body in the bath will not cause bath residues to dry or bake on.
The fact that spraying of the emergent body begins early means that relatively large amounts of water enter the preparatory bath, whereby the chemical composition of the latter is altered disadvantageously. The spray water causes the bath contents to overflow frequently in a dipping arrangement of the type described above employed for mass production, whereby a portion of the heated bath contents together with the chemicals is lost.
Accordingly, an object of the present invention is to improve the method of keeping parts such as motor vehicle bodies wet during preparation for painting in the manner described above in such a way that this system can be operated more economically and especially more cheaply.
This object is achieved according to the present invention by placing the part and/or body in a wet vapor atmosphere.
In a preferred embodiment of the present invention, a saturated vapor is used which forms wet vapor when it expands to the pressure of the air surrounding the part or body, said wet vapor sufficing to keep the part or body wet. Advantageously, this means that only small amounts of foreign liquid can enter the bath over a long period of time, thus avoiding overflow of the bath. Since the bath is prevented from overflowing, the associated heat losses are eliminated, permitting, on the one hand, more uniform temperature control of the bath contents and, on the other hand, a saving of energy.
Preventing the bath from overflowing has the additional advantage that the contents of the bath maintain their chemical composition practically unchanged over a long space of time. As a result, the consumption of chemicals per bath and part or body is considerably reduced in a mass-production dipping installation.
Accordingly, the present invention allows a considerable decrease in operating costs by saving operating means and energy.
These and other objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show for purposes of illustration only a single embodiment in accordance with the present invention.